Enhancement of light extraction from light emitting diodes

Contemporary design in engineering and industry relies heavily on computer simulation and efficient algorithms to reduce the cost and to maximize the performance and sustainability as well as profits and energy efficiency. Solving an optimization problem correctly and efficiently requires not only the right choice of optimization algorithms and simulation methods, but also the proper implementation and insight into the problem of interest. This book consists of ten self-contained, detailed case studies of real-world optimization problems, selected from a wide range of applications and contributed from worldwide experts who are working in these exciting areas.Optimization topics and applications include gas and water supply networks, oil field production optimization, microwave engineering, aerodynamic shape design, environmental emergence modelling, structural engineering, waveform design for radar and communication systems, parameter estimation in laser experiment and measurement, engineering materials and network scheduling. These case studies have been solved using a wide range of optimization techniques, including particle swarm optimization, genetic algorithms, artificial bee colony, harmony search, adaptive error control, derivative-free pattern search, surrogate-based optimization, variable-fidelity modelling, as well as various other methods and approaches. This book is a practical guide to help graduates and researchers to carry out optimization for real-world applications. More advanced readers will also find it a helpful reference and aide memoire.

Computational Optimization and Applications in Engineering and Industry

This paper presents a new class of multi-stub loaded resonators with flexibly controlled resonance modes, which are suitable for both tunable and nontunable filter applications. The proposed resonators, modified from a basic tri-mode resonator, include two quad-mode ones and a six-mode one. One of the quad-mode resonators is utilized to design a reconfigurable dual-band filter with tunable lower passband and fixed upper passband. The other quad-mode resonator is applied to design a bandpass filter (BPF) with very high skirt selectivity. The six-mode resonator is suitable for tri-band BPFs with individually controllable passband frequencies and bandwidths. All three circuits are theoretically analyzed and experimentally demonstrated. Comparisons of the measured and simulated results are presented to verify various applications of the resonators.

Novel Multi-Stub Loaded Resonators and Their Applications to Various Bandpass Filters

Sulfur(II)-containing polymers (polysulfides) combine flexible synthetic and processing techniques with a unique responsiveness to oxidants. Here, the polysulfide oxidative sensitivity is put into the biological context of the development of new anti-inflammatory therapies - the development of new anti-inflammatory methodologies, adopted interactions and the minimisation of foreign-body reactions - through the review of 50 years of research on polysulfide synthetic methodologies. Attention is paid to the identification of the most flexible and robust preparative techniques.

Polymers and Sulfur: what are Organic Polysulfides Good For? Preparative Strategies and Biological Applications.

A compact differential ultra-wideband (UWB) bandpass filter (BPF) with planar structure is presented. The circuit of the proposed filter is analyzed, showing that the differential-mode circuit, which consists of two short-ended stubs and an open-ended parallel-coupled lines, performs as a UWB BPF. While the common-mode circuit performs as a UWB bandstop filter, and the common-mode responses are suppressed across the whole UWB differential passband. A microstrip differential UWB BPF is designed, simulated and measured. Simulated and measured results show that the proposed filter has compact size (0.35λg×0.7λg), UWB differential passband (3 dB fractional bandwidth 119%) and UWB common-mode suppression (-10 db attenuation across 2.6-12 GHz).

Compact Differential Ultra-Wideband Bandpass Filter With Common-Mode Suppression

In this paper, a novel synthesis theory is proposed to design ultra-wideband (UWB) bandpass filters using 3lambda0/4 (lambda0 is the wavelength at central frequency of the filter) parallel-coupled line resonators. By using the first two resonant modes of the 3lambda0/4 parallel-coupled line resonators, this kind of UWB BPF can achieve a wide bandwidth larger than 100%. In order to alleviate the requirement on fabrication precision, aperture-enhanced coupled lines are introduced in the filter. A three-degree UWB filter with a midband frequency of 6.85 GHz is synthesized, simulated and fabricated. Measured results indicate that the filter is low loss in the passband, and the attenuations in the lower and upper stopbands satisfy the indoor limit issued by the Federal Communications Commission (FCC).

Synthesis and realization of novel ultra-wideband bandpass filters using 3/4 wavelength parallel-coupled line resonators

To design an ultra-wideband (UWB) bandpass filter with the fractional bandwidth (FBW) up to 110% (31%106%GHz), a new filter prototype consisting of multi-stage parallel-coupled stepped-impedance resonators (SIRs) is synthesised based on the transmission-line theory rather than the conventional multi-mode property Asymmetrical SIRs are employed instead of the conventional symmetrical/quasi-symmetrical ones, so that an extra degree of freedom is introduced in circuit parameter selection As a result, the minimum dimension of the coupling gaps between the adjacent SIRs is successfully enlarged to be more than 01%mm, which alleviates the requirement on fabrication precision A simple equivalent circuit for this filter prototype is represented in the form of distributed parameters and the corresponding Chebyshev filtering function is derived as well The relation between the number of poles in passband, N p , and the stage of the filter, n , is summarised to be N p =3 n +2 To validate the newly derived synthesis theory, a one-stage UWB filter is first synthesised to compare with the previously published results obtained by the electromagnetic (EM) simulator Furthermore, a two-stage filter is synthesised to successfully meet the Federal Communications Commission (FCC)+s indoor/outdoor spectrum specifications The fabricated UWB filter exhibits a compact size of 2658+mm in total length, low insertion loss (09+dB at 685+GHz), flat group delay (05+01+ns), good stopband characteristics (+S21+++40+dB at 1+2+GHz) and steep skirt property (+28+dB/GHz) as well It should be noted that the proposed filter prototype can be also used to realise aUWB filter with an FBW even greater than 110+

Synthesis of ultra-wideband bandpass filter employing parallel-coupled stepped-impedance resonators

A novel compact ultra-wideband (UWB) bandpass filter is developed by using microstrip stub-loaded dual-mode resonator doublets. The proposed doublet consists of two parallel but oppositely arranged stub-loaded resonators, and has a significantly widened passband. A UWB filter is designed by cascading three doublets, and eight transmission poles are obtained in its passband. The filter has a passband covering 3.3–10.4GHz, and exhibits sharp attenuations near its passband. The measured frequency response of the filter has a good agreement with the designed one, and the FCC’s indoor limit is satisfied quite well. The minimum strip and gap widths of the filter are larger than 0.1mm. Therefore, critical fabrication precision requirement or complicated backside-aperture-fabrication process is avoided.

A novel compact ultra-wideband bandpass filter using microstrip stub-loaded dual-mode resonator doublets

Manuscript received December 22, 1998. Manuscript revised March 9, 1999. † The authors are with the Department of Electrical Engineering, Kanagawa University, Yokohama-shi, 221-8686 Japan. †† The authors are with the Department of Elctronics and Electrical Engineering, University of Nottingham, NG7-2RD U.K. a) E-mail: anada@cc.kanagawa-u.ac.jp SUMMARY In this paper, outlines of the derivation of two recently developed finite difference beam propagation methods based on the higher-order Pade approximations are given to simulate the optical field propagation of tilted and turning waveguides. In order to investigate the accuracy and limitation for a propagation angle of these approaches, numerical results are presented for two benchmark tests. The present algorithms will offer, to our knowledge, the new beam propagation methods in optics. key words: beam propagation method, operator splitting method, exponential operator method, tilted waveguide

Very-Wide-Angle Beam Propagation Methods for Integrated Optical Circuits

A compact ultra-wideband (UWB) bandpass filter (BPF) with a controllable notch band is proposed and implemented for the application in UWB wireless communication system. In terms of a recently-proposed filter synthesis theory, a short-circuited-stub-loaded multi-mode resonator based UWB filter is designed to create an ultra-wide passband, within which a narrow notch (rejection) band is introduced by an external coupled stepped-impedance resonator (SIR). The location of the notch band is controlled by the proper selection of the high-low impedance ratio and electric length of the SIR. A simulative investigation exhibits that the external SIR is able to create narrower notch band than other conventional techniques, such as open-circuited stubs, spur-lines and embedded inline stubs. In addition, since the distortion of the filter characteristics, introduced by the external SIR at non-resonance frequencies, can be neglected, the proposed UWB notch filter can be implemented by the design of UWB BPF and external SIR respectively. As an example, an FCC UWB filter (BW: 3.1∼10.6GHz) with a WLAN notch band was designed, simulated and fabricated. A very good agreement between the measured and predicted filter characteristics validated the proposed filter prototype and corresponding design theory.

Design of compact notched UWB filter using coupled external stepped-impedance resonator

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